An electroluminescence element (referred to herein as [EL element]) is known as a light emitting element which utilizes an electroluminescence phenomenon. The EL element has a structure in which an EL material which becomes a light emitting material is sandwiched between an anode and a cathode and emits light at a wavelength according to the type of EL material.
When a certain voltage is applied between the anode and cathode of the EL element, a current flows between the anode and cathode and the EL material emits light at a luminosity according to the value of the current. Therefore, by controlling the value of the current supplied to the EL element, it is possible to make the EL element emit light at a desired luminosity.
A pixel circuit of a conventional display device includes a drive transistor which controls the value of a current supplied to an EL element in each pixel display devices in recent years, because gradation control capabilities at a high level are being demanded, the drive transistor is required to very finely control a current value. As a result, a technology for removing the effects of a variation in drive transistor characteristics has become important.
Various pixel circuits have been developed in order to correct the characteristics of a drive transistor (threshold value or mobility for example). However, as a result, the number of transistors or the number of control wires within a pixel has increased which is an obstacle to achieving high definition of the EL display device.
Therefore, a technology has been proposed in Japanese Laid Open Patent No. 2014-85384 for example which realizes simplification of required elements and wires using two transistors and one capacitor as a means for achieving an EL display device with high definition.